This invention relates to a lubricating method and apparatus for a circular knitting machine, and more particularly to a method and apparatus for the continuous lubrication of circular knitting machines for knitting generally tubular articles such as underwear and socks.
In general, a circular knitting machine comprises a plurality of needles arranged in a substantially circular row around the periphery of the machine. A rotating shaft is provided interior of and in engagement with the row of needles so as to revolve the needles around the periphery of the machine. A drum-shaped cam having a cam groove is disposed exterior of the row of needles. Projections protruding from the needles engage the cam groove so as to move the needles back and forth as the row of needles revolves. A cam holder is provided around the cam so as to fixedly hold the cam.
With such an arrangement, the needles arranged in a row around the periphery of the machine are moved back and forth with rotation of the shaft so that threads supplied from a thread supply source mounted above the machine base are knitted to produce a tubular knitted article which is discharged from a central region of the rotating shaft.
Conventionally, lubrication of circular knitting machines involves a method wherein lubricating oil is continuously supplied to the cam groove of the cam in the form of a mist via pressurized air delivery. This conventional mist lubricating method for a circular knitting machine, while having good lubrication performance, has a drawback in that practically all of the lubricating oil is scattered away from the lubrication location. Hence not only is there the undesirable effect of excessive lubricant wastage, but also there are environmental pollution problems such as damage to the knitted product and contamination of the surroundings due to the dispersed mist. Moreover, since a compressor is necessary to supply compressed air for creating the mist, equipment costs are substantial.
Another method for lubricating circular knitting machines which does not have the problems that are associated with mist oiling involves providing a nozzle in the cam holder for airless spraying of lubricating oil directly into the cam groove of the cam. The lubricating oil is sprayed intermittently in a pulsing fashion from the nozzle. This lubrication apparatus injects a fixed amount of oil for much less than a revolution of the needle assembly or row of needles. Although intermittent oil supply reduces wastage of the lubricating oil, the disadvantage is that lubricating oil is not spread equally to the projections of all of the needles passing around the cam groove. This results in nonuniform lubrication of the parts, and the machine thereby becomes susceptible to failure such as seizing, and reduced durability.
For the foregoing reasons, there is a need for a method and apparatus for the continuous supply of lubricating oil to a circular knitting machine by a means other than pressurized air. There is also a need to provide a lubricating method and apparatus for a circular knitting machine which can reduce wastage of lubricating oil to an insignificant amount, and which can spread the lubricating oil uniformly to all required locations without lubricating oil contamination of the surroundings, thereby preventing nonuniform lubrication and ensuring machine durability.